Starts, idles for a moment, then dies

[pancho88]

I've been working on a 1998 Legacy outback 5-speed that I purchased recently. After finally getting the starter to engage, the engine starts, runs for 2-4 seconds, then RPMS go way down and it dies. If I try to give it a little gas that kills in instantly. I've spent a good deal of time trying to get this thing started, could it be flooded? Also, the y-pipe is split (replacing soon), but could that be causing it to die? Maybe bad readings from O2 sensors, etc? Thanks.

[RobLog]

Running for a few seconds and dieing is often because a vacuum hose is disconnected. The most common one left unconnected is the IACV hose where it connects to the bottom side of the air intake. See photo.

[pancho88]

That fixed it. Thank you so much.